A typical vehicle steer axle assembly has a steering knuckle that includes a body, steering arms, steer axle, a brake mounting plate, and a spindle for a wheel hub, along with bearings, a bushing, and a king pin (see, for example, U.S. Pat. No. 6,623,019 to Davis and U.S. Pat. No. 7,740,253 to Ziech).
FIG. 2 illustrates a prior art vehicle steer axle assembly 30 having a knuckle 32 that pivots about a king pin 34 on a generally vertically inclined steering axis A2. Top and bottom bushings 36a, 36b are inset (for example, pressed) within aligned top and bottom king pin portions 38a, 38b. Top and bottom king pin portions 38a, 38b are located within a kingpin bore 40 of the knuckle 32, so as to allow the knuckle 32 to rotate relative to the kingpin 34 and to limit axial and radial movement of the knuckle 32 relative to the kingpin 34. Each top and bottom king pin portion 38a, 38b and their respective bushings 36a, 36b create a king pin joint where a lubricant G (e.g., grease or oil) is disposed.
Although there are self-lubricating systems currently on the market, these systems are complex and costly. Therefore, most existing steer axles are typically required to be manually lubricated at prescribed intervals. However, it is known that manually lubricating a king pin joint is time consuming, because it has to be scheduled, tracked, and results in vehicle down time. Consequently, OEMs (original equipment manufacturers) and truck fleet owners dislike the added cost, wait times, and overall inefficiencies in maintaining their truck fleets.
Therefore, what is sought is a less complex and less costly self-lubricating system that would be invisible to fleet owners and to vehicle owners in general. Such a self-lubricating king pin joint system would have to reduce overall fleet/vehicle maintenance costs by minimizing maintenance, increasing uptime, and maintaining strong product durability. This system needs to be able to accurately dispense the lubricant and avoid distributing too much or too little lubricant at intervals. Such a system would be enhanced if it could be completely replaceable or retrofitable on existing steer axles. Thereby, the system would provide an additional aftermarket opportunity for both retrofitting steer axles or possibly being sold as a replaceable or retrofitable king pin kit. Consequently, such a system would make existing steer axles service free, where aftermarket sales and profitability would be enhanced.